Textile



7 Sept. 3, 1963 D. s. ADAMS 3,102,323

TEXTILE Filed Aug. 26, 1958 Elly-1 L /g I /2 I Ellyn? 2 fl w L o g Q o 5B INVENTOR @7 DUSTIN s. ADAMS ATTORNEY 1 3,102,323 TEXTILE man. s. Adams wilmington,DeL, assignor tO-AE. I. du

Pontde Nemours-andCornpany, Wilniington, Del. a

corporationof Delaware t Filed Aug-2'6, 1958, Ser. No. 757,370

I This inventionhas to do with syntheticorganic polymers. More specifically, it has-to do with fibers,- filam'ents,

films, and the like of syntheticorganicpolymers'contain-.

ingadditives andwitha, process for introducingadditives into fibers, filaments, films, and the synthetic organic polymers.

Synthetic fibers are well known articlesdofcomrnerce andtheir use has become increasingly widespread during the pastseveral years. Suchfibers are in general based on synthetic organic polymers, and they show-anumber ofjadvantages which have ledto their wideacceptance.

In the tidal for-min which they are solclito the ulti- I ,mate user, most synthetic fibers and indeed' rna'nynatural fibers contain additives andrnodifiers 'offo ne sort Olffllb other. The most usual single additive'is a dyestufi. In

general, both natural;andsyntheticfibersare dyed by a number of different processes, all of which cause dye like composed of V molecules. orparticles either to adhere to the 'surface' of the fiber or to penetrate into the interior structure thereof.

In addition to-dyes,"many other additives and modifiers are also used in enhancing the properties-and appearance ofsynthetic fibers. Stabilizers are sometimes added to prevent or decrease deterioration of the polymer structure l ce,

Patented Sept. 3, 11963 One of the limitatidns of synthetic organic polyme rs 'f in application in the fields of textile fibers and filaments is that there have been many classes of dyestuffs, modifiers,

. and other additives which have not been successfully and permanently combined with the basic polymer structure because or alack of'affinity between the two substances. Moreover, in many cases the penetrationgof a modifier or additive into-the interior structure of the syn thetic organic fiber .or. filament is only partiaLr the concentration being heavy at the surface and very low or nonexistent at the core of the filament. In extreme cases,

the additive does not penetrate at all but merely adheres to the surface and is in dangerof being lost on repeated washings or wearings by abrasion or diffusion. Therefore, anyone who has wished-to dye'or otherwise modify or make additions to fibres, filan1ents,'films, and V Y J the like of synthetic organic polymers has had to take into account that the desired affinity may or may not exist between the polymerand the additive which he proposes to use. This has imposed serious limitations upon=the use of certain dyestuffs, particularly in the preparation of textiles from synthetic'fibers and filaments. Also, I

while it has proved possible todevelop antistatic agents, wettingagents, light stabilizers, and thelike for applica tion-to synthetic fibers and filaments, the permanence of such applications has not always' been satisfactory.

It is an object of the present invention to provide fibers,

Z filaments, films, and the like of syntheticorganic polyon exposure to light, ultraviolet radiation, orheat. -Anti- [yellowing agents havebeen employed. Opacifying agents and delusterants areadded'to increase the covering power or reducethe .sheen ofyfibers and filaments. Resins, other 'polymergcro'ss-linking agents, and thelike are also}addedto fibers or filaments or to fabrics constructed from these materials in order to promote wrinkle resistance, crease resistance, ease of laundering, and other physical properties. siinilar additives and modifiers are also applied to films of synthetic organic polymers for like purposes. Frequently, dyestuffs are applied to synthetic-organic "fibers and filaments which have already been subjected to a process of orientation by cold-drawing. .In addition,it

has been recognizcd,'as for example in US. 2,278,888, 7 t issued April 7, 1942, to E. V. Lewis, that itispossible to dye undrawn filaments and to take advantage thereby of the greater ease of diffusion of adyestuif into the structure of the filament or fiber. Equally well, it is mers which contain higher concentrations-and in the radial dimension more uniformly distributed quantities of various additives and modifiers, such as dyestuffs, antistatic agents, light stabilizers, and cross-linking agents in which the additive or modifier more completely penetrates into the interior structure of the polymer than has heretofiore been possible, including additives which cannot otherwise be combined with the polymer. A further ,ob-

ject of this invention is to provide a process by which additives and modifiers can be infused into the interior of synthetic organic fibers, filaments,'filrns, and the like so that the permanence of the additive is greater than is the case when such additives aremerelysurface coated onto thefilarnent. A further object is to provide a process by which synthetic fibers and filaments and films can be more deeply and effectively dyed by a wide variety of dyestuffs, including those which are not substantive or possessing of any affinity for the polymeric structure itself or which lack :dififwsibility. A still furtherobject is to provide a process by which synthetic'organic fibers and known to apply other additives, such as antistatic agents, 7

dye mordants, dye-site-formers, and the'like toa drawn or an undrawn fiber or filament. In addition, crosslinking agents and polymer-forming reactants, and the like have been added to a polymer structure orcoated I onto the surface of a synthetic polymer filament to permit 7, modification of the properties thereof 'by' cross-linking filaments and films can be simultaneously oriented and have applied a modifier or additive in deep penetration .into theint-erior structure of the polymeric material. An-

other object is to provide a process by which synthetic fibers can be oriented continuously at drawing temperaor further polymerization," as, shown, for example, in

As has already been indicated, such additives archercarriers which are partial solvents or swelling agents for the Epolyrner and by other processes which havein com mon that they depend upon a natural and mutual afiinity between the modifierand the polymer itself. I

.U.S. 2,430,953, issued November .18, 1947,.to A. K.

Schneider. r I

mally applied to the oriented fibers or filamentsbut can,

tures lower than those heretofore found operable. Other objects will become apparent-from thedescriptionof the invention and examples which follow.

These; objects are achieved in highly'and uniformly oriented structures, such as filaments, filmsand the like of substantially uniform diameter or thickness consisting essentially of synthetic organic polymeric material having a modifying agent distributed therein in deep pene .treition into the structure transverselygto the axis of o-ri'en:

, tation, the said modifier being present in-amultiplieity' of short-length regions ofnon-uniforrn concentration along the said axis of orientation, the variations occurring with a frequency of at least about 10 per inch and preferably from 500 to. 20,000perinch. It has been foundthat products of the type useful in the present invention can be prepared by a process for infusing a modifier with an orientable synthetic organic polymeric structure, comprising the. stepsof tensioning the. structure prior to complete orientation'while in contact with a surface-crack-pr'omot- 'olution.

ing agent and orienting the structure by drawing while maintaining it in simultaneous contact with both a crackor fissure-promoting agent and the modifying agent, whereby the modifying additive is imbibed into the interior of the said polymeric structure.

It has been observed that, in the operation of the process according to the principles set forth above, and as shown in detm in the examples which follow, the modifier is .taken up by the polymeric structure during the process of orientation. For satisfactory results, the orientation step should proceed by a sharp-neck process rather than a long-taper process which is frequently employed in drawing or elongating synthetic fibers. The sharp necks suit-able for producing the desired products of this invention are initiated by the cracks caused by the combined action of tension and surface-cnack-promoting agent.

'It has been further observed that modifiers introduced by the present process are distributed within the interior structure of the final oriented material in a unique and novel manner. In the ease of a filament, the penetration in the radial sense is deep-much deeper and more uniform than conventional surface-dyeing, for example. However, the distribution of modifier in the axial sense is non-uniform, and occurs in short length fluctuations randomly distributed in high-frequency recurrence along the length of the filament. Without wishing to be bound by theoretical speculations, I believe that the modifier penetrates into the interior of the structure through the cracks which appear randomly and at closely-spaced intervals in the surface of the polymer when it is tensioned in the presence of the crack-promoting agent, and that the extent, depth and permanence of the penetration is augmented by the freshness and lability of surface of the polymer in the area of the crack.

The non-uniform axial distribution of modifier in the products of this invention is an unexpected and valuable property, useful in a variety of applications, and variable to a considerable degree. The effect of-the modifier in the final product can be controlled by altering the periodicity of the fluctuations in concentration of modifier. This may be done by selection of a cracking agent to give more or fewer cracks per unit length of polymer structure, or by changing the rate of drawing, or, to a lesser extent, by changing the temperature of drawing. The final concentration of modifier may be varied by changing the concentration of modifier in the cracking bath. Other methods of control, involving interaction of temperature, rate of treatment and the like, are also possible.

In addition, the frequency of fluctuations of modifier concentration is Very much greater than has hitherto been achieved in operations involving synthetic fibers and films. Indeed, such high-frequency fluctuations have not, up to now, even been considered attainable. Novelty yarns have in the past been made with fluctuations in dyeability, and different dyes have been applied to a single filament at spaced intervals. However, such elfects have been based upon relatively long range differences, involving changes every half-inch, inch, or foot along the filament. The fluctuations of the present products differ from these values by one to five orders of magnitude. Former products had fluctuations readily and intentionally visible to the naked eye. The present products have fluctuations which range from just barely detectible to the naked eye, up to those which require an electron microscope for res- Such a range of fluctuations offers great advantage in control of properties of the final products. In addition, as the examples show, modifiers can now be employed which have not heretofore been satisfactory because the modifier could not be permanently combined with the polymer. Furthermore, fluctuations in modifier content can now be achieved in combination with a polymeric structure which is uniform in diameter or thickness and is uniformly oriented as well.

The product of the invention may be in the form of fibers, filaments, films, and the like prepared from synthetic organic polymers which are orientable by a sharpneck drawing process. These structures contain a modifying additive which may be one or a mixture of those hereinafter described distributed non-uniformly and nonhomogeneously along the length of the filament or film, and when magnified show a short-range variation in concentration along the length of the polymeric structure. These non-uniformities are of very short length and occur in general from about 10 to 20,000 per inch and preferably from 500 to 20,000 per inch. Each section of modi fier concentration results from a crack or fissure. It will be apparent therefore that there will be as many dye or other modifier concentrations as there were cracks or fissures produced by drawing.

The effect of the modifier can be controlled by concentration such as by, for example, dye depth, electrical conductivity, formation of voids and the like. Two or more modifiers may be imbibed successively or they may be imbibed simultaneously. When two or more modifiers are introduced into the fiber successively they may be of such a nature as to react within the fiber where they meet for special purposes such as precipitation, formation of a large molecule, formation of gas, reduction of metal salts to the metal, etc.

The invention will be more clearly understood by reference to the accompanying drawing in which FIGURE 1 is a diagrammatic view of a yarn undergoing a short drawing of the type suitable for the present invention. FIGURE 2 is a similar view of conventional drawing in which the drawing section is represented by a long taper. FIGURE 3 is a diagrammatic section of apparatus suitable for carrying out the invention. FIGURE 4 is an enlarged view of a filament in which cracks have been introduced by drawing about 1.1X in a crack-enhancing liquid. FIG- URE 5 is a diagrammatic view of the filament of FIGURE 4 which has been contacted with the crack-enhancing liquid, but has not been drawn appreciably. FIGURE 6 is a diagrammatic cross-section along the line 66 of FIG- URE 4 of a yarn having a brittle outer shell suitable for treatment by the present invention.

In all figures, 1 represents the undrawn yarn and 2 is the drawn yarn. In FIGURE 3, a container 3 is supplied with a crack-enhancing liquid 4 and immersed in the liquid are guide roll 5, and a pair of driven draw rolls 5A and 5B which draw the yarn 1 as it passes through the liquid 4. In FIGURE 4, the filament 1 is drawn 1.1X to produce cracks 8. Between the cracks are raised portions 9. In FIGURE 5 the incipient cracks or fissures are indicated as 8. In FIGURE 6, 6 represents the brittle outside shell of the filament and 7 is the inside core as will be more completely described hereinafter.

In FIGURES 1 and 2 the angle A should be of the order of 30 to and the length of the draw neck should be short; i.e., distance B should be less than 3 times the diameter D of the undrawn filament or thickness of the undrawn film. In other words should be less than 3.

The phenomenon of surface cracking in unoriented synthetic polymers is known and is described in an article by H. J. Woods appearing in the Journal of The Textile Institute Transactions, vol. 46, pages 629-631, published September, 1955. The article is concerned with surface cracking of nylon, and the author lists a number of liquids which were observed to induce cracking at the surface of the yarn. The observations set forth are believed to be substantially accurate, although in the present invention it has beeen found, contrary to Woods results, that ethanol, for example, is a good crack-promoting agent. Woods also describes a multiple-neck drawing process, leading to a highly drawn fiber of uniform diameter with some surface roughness.

- in the process of Woods.

ducing cracks into nylon filaments.

. The process of the present invention, however, is based on new, additional features which are not comprehended present invention it is possible "to' obtain many results which have hitherto not been obtainable. The present invention has the feature that during the drawing process the fiber is exposed tofa modifying'additive which surprisingly and" unexpectedly is infusedra'pidly and th-or- I oughly into the polymer structure. This infusion of the additive does not appear to be particularlydependent upon substantiveness between the polymer and is not excluded. The surprising nature of the present invention may in part be illustrated by the fact that basic dyes, which have hitherto been considered: as quite.

useless in coloring polyethylene terephthalate fibers and filaments can now be thoroughly, uniformly, deeply, and

, instantaneously dispersed into the fiberor, filament structure of this polymer regardless of the lack of any chemical affiinity between the two materials. 7 1

. This phenomenon in itself is of .great utility because it is highly desirable to be able to color polyethylene terephthalate with basic dye colors. It is not, of course, intended that the foregoing statement indicates any limitation on the breadth or scope of this invention; Similar procedures produce desirable products using other modi fying additives, other dyes and with other polymeric 3 For example, it is extremely difiicult in genmaterials. eral to dye or color films and filaments "of aliphatic polyhydrocarbon, e.g., polyethylene, with anyclass ofcolorin-g materials except by the addition of pigments directly to a molten mass of the polymer" before extrusion into filamentary form. This melt dyeing process is operative, but" the range of coloring materials which can be employed "at the high temperatures required is necessarily limited. Now, however, it is found that a wide number of different coloring materials, including dyes, lakes mordants, and the like can be infused into poly- ]hydrocarbons, such as polyethylene and polypropylene,

in filamentary or film form by the process of the present invention and thata'wide range of colored filaments,

the first place, the liquid chosen should not in general be a solvent or strong swelling agent for the polymer. Solvent action by a liquid necessarily eliminates the formation of surface cracks.

Desirable cracking agents in'general have a low surface tension. Prefe'rred compositions are those with a surface tension measured relative to air of not greater than 60 dynes per centimeter measured at the temperature at which it is proposed to employ the agent. The desirability of a low surface tension is not completely understood, but it is possible that the cracking agent aids in the progress of the modifying additive from the bulk liquid phase down into the cracks and;thence into the interior structure of the polymer. In general, nonaqueous cracking agents are preferred. Water by itself was found not to be a satisfactory cracking agent, except possibly for especially treated polymers. Preferably, the cracking solution should contain at least 10%..

by weight of a non-aqueous organic liquid, and for many cracking agents, 25% concentration is still better.

1 The cracking agent should also preferably have a high tendency to wet the surface of the filament being cracked. 'In general, the wetting angle between a liquid and a polymer is determined by measuring the contact angle between a film of the polymer and a droplet of theliquid. Such a wetting angle is normally measured so as to include rather than exclude the liquid phase; that is, the wetting angle of a poor wettingagent will be more than 90". For the practice of the present invention, it is preferable that the wetting angle be less "than 90, and under many circumstances it is found that wetting angles as low as are obtained with the best cracking agents.

[of the present invention to employ as a cracking agent fibers, films, and the like are thus obtainable. Moreover, whereas other attempts to dye or otherwise color drawable' polyhydrocarbon structures have resulted in only slight surface coloration, the products ofthe present invention which are made employing polyhydroca'rbon polymers are deeplyand uni-fonmly colored throughout the structure of the filament and the color; shows no tendency to rub off-or wash off. Similar difliculties have been encountered with'melt-coloration of other fusible polymers, and with solution-coloration of'polymer solutions prior to spinning, .wherethe coloring agent or.

other modifying additive is damagedby heat or chemical action of the solvent.

a mixture of liquids. Under such circumstances the choice of a. suitable mixture and the selection of the relative concentrations of the ingredients making up the mixture will be governed by the same criteria already discussed, that is, low solvent power, low surface tension, and low Wetting angle.

When a mixture of liquids is employed, it is usually preferable that the'liquids (not considering the-modifying additive) form a single liquid phase. For best results, it is further preferablethat the additive be soluble in the cracking agent. It may be observed that certain liquids which have some solvent or swelling, tendency on the polymer can be employed if they are otherwise suitable, provided that the contact time between the liquid and the polymer is kept short; that is, the cracking must occur before the swelling or plasticizing action has a chance to occur, since such action would prevent the formation of fissures or cracks, therefore, the entire process must be completed before any observable degree of plasticization occurs. It should be understood that the crackor fissure-promoting agent can also be the modifying agent which is 'infused' into [the polymer Surfaoe-cracking agents suitable for the practice of .rner. One I extremely simple criterion is available, and

that is merely to applytests'similar to those described in the article of Woods and observe whether placing the'filament .inthe liquid under slight. tension causes cracks. However, other criteria are'also available. In

structure during the process of this invention.

The present invention is applicable to a widenumber of different synthetic organic polymers. Among these are polyamides, polyesters, polyurethanes, vinyl polymers and polyhydrocarbons. So far as is known, any synthetic organic polymer capable of being formed into filaments which can be cold-draw oriented by a process involving a sharp neck are suitable for the present invention.

q The following examples are given by way of illustra tion.

It is to be understood, however, that the crack or fissure-producing agent given in the examples may be replaced ,by others of those discussed at the end of the examples. Likewise, any modifying agent or additive disclosedhereinafter may be substituted in like amount It is possible and within the scope as shown in FIGURE 1 and develops cracks or fissures in contact with the liquid through which it is drawn. The polymer should not be soft and tacky, or elastic, or highly plasticized unless surface treated to produce a brittle outer skin. This case-hardening treatment of polymers varies with the chemical structure of the polymer but ultra-violet light, halogens, sulfur-containing gases, vulcanizing agents, and the like have been used for this purpose. In the examples and elsewhere C.I. is an abbreviation for Color Index.

EXAMPLE I A sample of polyethylene terephthalate as spun and prior to drawing was placed in a purified hydrocarbon in kerosene range and hand drawn. It was observed that the fiber cracked during the drawing process. This experiment was conducted with equal results at three different temperatures, -l C., 0, and +13 C. In a similar experiment the same fibers were placed in water at 0 and 13 C. At 13 C. drawing proceeded by conventional process, and there was no cracking observed. At 0 C. some cracks developed, but they would not propagate around the surface of the filament and drawing was unsuccessful.

EXAMPLE II A monofilament of undrawn polyethylene terephthalate of 1800 denie-r was immersed at room temperature in ethanol containing approximately 2% of a basic blue dye C.I. 42,595. The monofilament was drawn 6x by hand, and an intense blue color developed in the monofilament. A portion of the monofilament was crosssectioned, and it was observed that the penetration of the dye was very deep, the color being uniform except at the very core. This deep penetration into a very heavy filament was unusual and unexpected. The dye was found to be fast to washing in spite of the fact that basic dyes in general are not satisfactory for dyeing drawn polyethylene terephthalate. The blue color was very much darker than a control filament which was drawn by conventional process and then immersed in an equivalent solution of the basic dye in ethanol. This latter filament was practically colorless after washing.

EXAMPLE III A cracking and drawing dye bath was prepared by mixing 80 parts of ethanol and 20 parts of water by weight with 1% of a basic green dye, C.I. 42,000. A sample of undrawn polyethylene terephthalate yarn containing 34 filaments was machine drawn (FIG. 3) through this dye bath to 5X its original length, to give a drawn yarn of 70 denier. The dye bath temperature was approximately 15 C. The feed rolls operated at 9 yards per minute peripheral speed and the draw rolls at 45 yards per minute. This particular dye was chosen because it has little or no dyeability on conventionally drawn polyethylene terephathalate yarns or on undrawn polyethylene terephthalate. However, in the present example a deep rich green color was obtained. Under the microscope, it was seen that the coloration was present in discontinuous sections along the filaments. The dyed sections alternated with undyed sections with an average frequency of about 500 per inch.

EXAMPLE IV A film of undrawn polyethylene terephthalate was placed on top of a piece of taffeta fabric woven from Dacron polyester yarn. The sandwich of film and cloth was soaked heavily with an alcoholic solution of a basic green dye, CI. 42,000 of a composition identical with that prepared for the previous example. This wet layered combination was fed through the pinch of a rubber mill, and Where the cloth threads contacted the film under the pressure from the mill there was suificient pressure to cause cracking, drawing and orientation, and deep dyeing occurred at those points. Little or no dyeing occurred at other points. The result was that the film took on a patterned effect comparable to the weave of the fabric, with great dye depth differences between the points of pressure and the points of no pressure.

EXAMPLE V A room temperature solution of 5% acrylic acid in ethanol was employed as a cracking bath and modifying additive. A sample of undrawn polyethylene terephthalate ribbon was hand drawn through the bath. The solution caused cracking, and the ribbon drew to a uniform denier and was highly oriented. Following the drawing process, the ribbon was after-dyed by normal procedures using a basic green dye, C.I. 42,000, and a deep color resulted. The acrylic acid acted :as a dye fixer for the fiber. The same dyeing treatment was tried on another sample of ribbon after washing it thoroughly and carefully in water to remove all surface traces of acrylic acid. No difference in dye depth was seen between the two samples, indicating that the acrylic acid had penetrated thoroughly into the interior structure of the ribbon.

EXAMPLE VI A sample of the same multifilament yarn employed in Example III was machine drawn through a bath of 100% ethanol containing 1% of a basic green dye, C.I. 42,000. This process was run at a higher speed than before, the draw rolls operating at a peripheral speed of 327 yards per minute. The dye depth obtained was equivalent to that obtained in Example III. The frequency of fluctuations was too great to be resolved with an optical microscope. A further experiment was performed employing a dye bath containing 25% ethanol and 75% water with the same concentration of dye as before. In the second bath, cracking proceeded as before, and the fibers drew to the same deep green color. Microscopic examinations showed longer fluctuations, about 60 per inch. However, when a third bath was made up, containing 5% ethanol and water, with 1% of the basic dye, it was found that adequate cracking did not develop, dye depth was very light, and the process of this invention could not be performed in a satisfactory manner. The cracks were separately visible to the naked eye, spaced at intervals from /2 inch to 2 inches.

EXAMPLE VII The sample of undrawn polyethylene terephthalate yarn employed in this experiment had been specially treated to provide a surface which was readily cracked. The procedure consisted of quenching of the threadline from the melt spinning process with vapors of S0 gas. The surface of this filament was much more brittle than conventional undrawn polyethylene terephthalate. It was found possible to perform the cracking and the infusion process of the present invention on this specially treated yarn using a water bath containing a basic green dye, C.I. 42,000. Similarly, this yarn could be cracked and drawn in air without any water present, although, of course, it was not possible to infuse a solution of a modifying additive'into the polymer structure in this manner. However, gases or vapors could be infused in this way.

EXAMPLE VIII A sample of undrawn polyethylene terephthalate tow was ozonized with 2% ozone in oxygen for 60 minutes at room temperature. This specially embrittled yarn was hand drawn through a mixture containing methyl acrylate, ethanol, and aqueous ferrous sulfate. During the drawing, which proceeded with the formation of cracks, the methyl acrylatew-as infused into the interior structure of the yarn. The tow was dried and then dyed with a violet disperse dye, 1,4-diamino-2,3-dichloroanthraquinone, for 30 minutes. The shade obtained was very deep, whereas, the control without the crack drawing process dyed to only pale violet color.

' was present.

. 9 in EXAMPLE 1X "contained also 2% of a basic green'dye, C.I. 42,000.

Undrawn polyethylene terepht-halate was infused with potassium dichromate in accordance with the present invention, employing a bath of ethanol and 75% water by Weight, containing about 2% by weight of the salt. The potassium dichromate infuscdinto the interior structure of the yarn during drawing and gave a highly drawn polyethylene terephthalate fiber of a rich orange color. The presence of this highly reactive inorganic chemical provided good fixative'powers for other modifiers for the fiber which could be introduced following the drawing process.

' EXAMPLE X A solution of nickel chloride in a mixture of 75 ethanol and 25 water was infused "by the process of the present invention into undrawn polyethylene terepih- .thalate. This sample as drawn was substantially uncolored. The yarn sample was then wiped dry with a towel to-remove the last traces of thedr-awing bath. The

dry yarn was then placed in a solution of sodium borohydride inwater. This chemical is a strong reducing agent for nickelr "Ilhe filaments promptly developed a full gray color, indicating the reduction of nickel to the metallic state.

taining the nickel. The nickel was present in regions of EXAMPLE x1 This example is similar in principle to Example X above, in that nickel chloride was again imbibed into an undrawn yarn of polyethylene terephthalate. However, in this experiment, successive imbibitionwas practiced in the following manner; Two diiierent baths were made up, the first contained nickel chloride in ethanol and the second contained sodium borohydride in a 50-50 mixture of ethanol and water. The undnawn yarn was immersed in the'nlckel chloride bath and partiallylcrack-drawn dur- 1 ing which process it imbibed nickel chloride into the interior of the yarn. *Theyarn'was not drawn to completion but was removed the first bath and the surfacewas rinsed-free of nickel chloride solution. Then, the yarn was immersed in the sodium borohydride bath and crack-drawing was completed." The; fiber turned black to dark gray durin'gfthe process.

intermittent along the threadline and was due to inter- The dark color was in weight duet'o calcium chloride take-up as determined gnavimetrically. The saltacontaining filament was dried under vacuum to remove all water, weighed, and then a exposed to air at 85% relative humidity. The water takef up was measured, and it was found that .the drawn filaments gained 12% in weight based on the polymer. This may be compared with the moisture regain of conventional polyethylene terephthalate drawn yarns of less than I.

1%. It was possible to remove the calcium chloride modifier by boiling the filaments .insoapy' water and Filaments preparedin this manner showed a much lower electrical resistivity than filaments not congredients, both of which were mild plasticizers for the filament.

varying concentrations, fluctuation at least 5000 per inch.

The same quantity of calcium chloride was taken up as before, but in the extraction process to remove the calcium chloride the salt leached out, while surprisingly the dye remained in the polymer structure as: shown-by the intense green color which was not substantially modified by thewalshing which removed the salt.

' EXAMPLE XIII A sample of undrawn polyethylene terephthalate filament was d-nawnby the process of the present invention employing as a cracking and infusing bath a solution of dimethylform-amide containing 5% iacrylom'trile monomer with an azo catalyst present. It was ttound necessary in this operation to draw the filaments immediately upon immension to avoid over-exposure to the cracking ind In the drawing process, the filament was run out :of the bath and around a pin held at between 7 0 and 80 C. High tension was required duringthe drawing process, and the resulting drawn fiber was cloudy, showing the presence of a 'secondstructural ingredient in the polymer. When the catalyst was presentthe acrylonitrile became polymerized and no longer functioned as a plasticizer. A control was run under identical circumstances, except that the catalyst was omitted. Under thesec1r,

cumstances, the fiberdrew with very low tension and was highly plasticized. The highly plasticizednature of the control was consistent with the presence of unpoiymerized acrylonitrile which continuedto function as a plasticizing agent. The pl-asticizing nature of acrylonitrile monomer was confirmed by employing infrared analysis to study the pickup of this material. If undnawn polyethylene terephth-alate is drawn in a bath as above, and

if the drawing is performed immediately upon contact with the solution, infrared analysis shows. that acrylonitrile monomer is infused into the polymer structure at a much higher percentage than is possible by merely soaking drawn or undrawn polyethylene terephthalate with acrylonitrile monomerp If the acrylonitrile solution is kept in contact with the undrawn yarn for. two minutes prior to drawing, then no. crack-drawing is observed and the pcncentage of monomeric acrylonitnile which is picked up is shown by infrared analysis to be equal to that obtained by normal soaking.

' As has already been indicated, it is possible toimbibe simultaneously two or more liquids or modifying additivesinto a polymeric filament during the drawing proc- 688.

It is also possible and one of the valuable modifications of the present invention to perform successive bibition of two or more different modifying additives. The following examples illustrate-successive imbibition.

, A sample of undra-wn polyethylene terephthalate yarn of p 34 filaments was used in the followingexamples.

rinsing inethanol. Complete removal of the calcium chloride was shown by. gravimetric determination which indicated thatthefibcrfhad neturned to its original weight befiore drawing. Inrunner. experiment it was found that the moisture regain" of the washed filament was equivalent to the moisture regain of conventional polyethylene terephth alate filaments. In another experiment, the same procedure described above. was repeated except that, in

addition to the calcium chloride, the crack-drawing bath EXAMPLE XIV Four cracking baths were made with the following composition. Each bath contained 50% by weight of ethanol and 50% by weight of water. In addition, the-first bath contained 1% by weight of a yellow basic dye C.I.. 41,000; the second bath contained 1% by weight of CI.

. Basic Red 14; the third bath contained 1% by weight of a blue basic dye, C.I. 42,595, and the fourth bath contained no dyestufit. The undrawn yarn was immersed first in the yellow bath and partially drawn to imbibe the yellow dye in some sections of the yarn. The fiber was then removed and the residual dye bath was wiped ofi.

The fiber was-then immersed in the red dye bath and drawn partially somewhat sfurther. The same process was repeated in the other two remaining baths, with the yarn being drawn to completion in the final clear ethanol water bath. 7 In each dye bath, duringthe cracking and drawing process, the fiber imbibed the dyestnff withwhich it was in The 5 contact in various sections along the threadline. sections which cracked and imbibed wene randomly dis:

tributed. The result was a multi-color dyed highly drawn filament of polyethylene terephthalate, approximately ,70

denier, 34 filaments, which contained in random distribution segments dyed yellow, red, blue, or not dyed at all. Since only approximate control was exerted to give uniform imbibition of the three dyes, the resulting yarn had a dark brown appearance to the naked eye. However, when viewed under a microscope at 50X it was quite easy to distinguish the separate portions of the filament which had been dyed with the individual colors. The distribution was random within each filament as well as within the total filament bundle.

A great variety of modifying agents has also been added to undrawn polyethylene terephthalate and other fibers from many cracking baths particularly those comprising ethanol alone or mixtures of water and ethanol. As antistatic agents, N-vinylpyrolidone and a surface active organic phosphate ester are satisfactory when applied to both fibers and films. Sodium styrene sulfonate has been added to fibers to provide dye sites and anti-static properties. Acidic dyes such as orange, C.I. 18,875, have been applied from ethanol-water mixtures containing 50% by weight of each liquid to give extremely deep colors.

In addition, other cracking liquids have been employed. Those which have been found useful in application to undrawn polyethylene terephthalate filaments include kerosene, Ultrasene, perchloroethylene, methylene chloride, methylene iodide, carbon tetrachloride, and ethyl cellosolve. Experiments with hydrocarbon solvents have established that they are fully equivalent to ethanol and ethanol and water mixtures. It is desirable that the modifying additive be soluble or readily dispersed in the solvent. Halohydrocarbons have been found to be cracking agents, but because of a tendency toward crystallizing action, they must be employed carefully and the contact time with the undrawn filament must be kept short. Similar precautions must be observed with plasticizing agents. In addition to ethanol, methanol and other lower alcohols have been found to be satisfactory. Many liquids have been found which are less satisfactory cracking agents for polyethylene terephthalate. These include phenol, 100% formic acid, trifluoroacetic acid, 100% acetone, benzene, dimethylformamide, and o-cresol. All of these, because of solvent or plasticizing action, can be employed only with extreme care or in a diluted state.

Other synthetic organic polymers have been found to be operative for the present invention in accordance with the principles already set forth. The following examples illustrate specific applications employing polyhexamethylene adipamide.

EXAMPLE XV A sample of undrawn 66 nylon yarn was placed in a cracking bath consisting of 100% ethanol, containing 2% of a basic green dye, C.I. 42,000. The yarn was drawn to give a highly oriented, 70 denier, 34 filament yarn which contained a high concentration of the green dye, giving EXAMPLE XVI A sample of undrawn nylon was drawn by the process of the present invention employing a cracking bath containing ethanol and water, 50% each by weight, and 1% of a blue basic dye, C.I. 42,595. The filament cracked readily and was drawn in the bath. The dyestufii infused into the interior structure of the yarn and gave an intense blue color much deeper than that obtained by contacting either the drawn or the undrawn nylon filament with the dyestulf bath.

The following additional cracking agents have been found to be successful in performing similar experiments using 66 nylon: acetone, dimethylformamide, dimethylsulfoxide. ethylene chloride. methyl ethyl ketone, methyl isobutyl ketone, and dimethylacetamide. With all of the above cracking agents, absorption of dyestuffs, ultraviolet stabilizers, dye site additives, cross-linking agents such as formaldehyde and the like was satisfactory. The following cracking agents have been found to be unsuccessful: Ultrasene (a purified HQ in kerosene range), silicon oil, acrylonitrile, carbon tetrachloride, and cyclohexane. Tetrahydrofuran was found to be operative if care was taken to avoid prolonged contact of the undrawn nylon filaments with the liquid which is a slight plasticizing agent for the polymer.

The following examples show operation with other synthetic organic polymers.

EXAMPLE XVII A sample of undrawn poly(meta-phenylene isophthalamide) was drawn by the process of the present invention in a bath containing 50% by weight of ethanol and 50% by weight of water with an additional 5% of formic acid. The bath contained 2% by weight of a basic green dye, C.I. 42,000. Undrawn filaments were run through the dye bath and cracked and drawn. During the drawing the filaments imbibed the dye to give a good depth of green color. The yarn was then heat-set by running it over a hot pin at 120 C., giving a filament with a boil-oif shrinkage of only 3%.

EXAMPLE XVIII Filaments of quenched polypropylene were spun with a residual draw of 2X. These were drawn according to the present invention through a bath of the same composition as that described in the preceding example. Normally, it has not been found possible to obtain coloration at all with this dyestuif on polypropylene, but in the present operation a deep green color was obtained. This infusion dyeing process is particularly advantageous with this and similar hydrocarbon polymers, since there are very few ways in which such filaments can be dyed.

EXAMPLE XVIV A copolymer of polyacrylonitrile polymerized from a mixture of 94% acrylonitrile and the residue methyl acrylate plus sodium styrene sulfonate was spun into filaments. When the filaments were tensioned in ethanol, a few surface'cracks developed. A 10% solution of dimethylformamide at 10 C. in ethanol was found to be a better cracking agent, and when the filaments Were stretched 1.1X in this bath the surface became heavily cracked, developing a white appearance. When 1% by weight of a basic red dye, C.I. Basic Red 14, was added to the bath and the fibers cold-drawn therein, a deep intense red color was obtained in the drawn filaments.

EXAMPLE XX Filaments of a polyurethane from ethylene bischloroformate and piperazine were spun and then cold-drawn to 1.5X their original length in a cracking bath consisting' of a mixture of lauryl alcohol esters of phosphoric acid. The bath contained 5% of a basic red dye, C.I. Basic Red 14. Good penetration of the dyestuif was observed. Other equivalent cracking baths included lauryl alcohol, decyl alcohol and kerosene.

EXAMPLE XXI A series of experiments were performed in which the effect of surface tension of the cracking bath was investigated. In all of these experiments, undrawn polyethylene terephthalate yarn was crack-drawn to 4X its original length to give a yarn of 70 denier, 34 filaments after the complete processing. The dye used in all cases was C.I. Basic Blue 9. The first set of experiments illustrates the effect of changing surface tension by employing mixtures of acetic acid and water at different concentrations. The results are shown in Table I, and it will be seen that I 13 the best processing and best infusion of dyeing was achieved when the surface tension of the bath was below 60 dynes/cm. I i i I i s Table I i The second series of experiments employed four different cracking baths, all of the same surface tension; namely,

46 dynesper,centimeter A 1% dye bath of bluebasic dye;was,employed. The yarn was as before. In all these baths of the same surface tension, substantially the same dye depth was obtained.

' Table 11 DYE DEPTH WITH DIFFERENT, Barns summon TENSION- cording to the present invention.

. 7 Percent' Surface w i Bath components composi tension, Temp, Dye depth tion dynes/ C. i V

Ethanol/water 103/89 .6 46 27 Methanol/Water. 17 .5/82 5' 46 27 substan- Acetone/water- 14.0/86 .0 46 27 tlally equal.

Acetlcacid/water 260/741] 46 1 27 From these results it Will b e seen that in order to prac-' tice. the present invention in its most advantageous aspects, the surface tension of the cracking baths should be below6O for conventionally spun fibers.

This has. been found to be true regardless of'whether apolyester,

"a polyamidea polyhydrocar-bon, a polyacrylonitrile, or other polymeric material is employed. i

It will be apparent from the above examples anddisclosure that no exact list of cracking agent-scan begiven A simple test,

which are operable for all polymers. however, may be carried out to determine: the suitability of .a given liquid fonthispurpose by dissolving a dye in the liquid, wetting the filament or film Withthe solution so prepared and drawing thesame 1X or 2X. The material is then Washed in Water or in a'solvent for the liquid but not for the polymer, and if the dye is removed the liquid is not suitable. On the other hand, if thedye can not be washed-out, it inevitablyfollowsthat'cracks or fissures have beenformed and the dye has been imbibed therein and theililquid tested is satisfactory for the purpose. L

, The precedingexamples have given some indication of the applicability of the "principles ofthe present invention to a number of specific embodiments. However, it should not be considered that the examples in \any way Ide-fine .all the limitations of the present invention. In tfact thepresent invention is applicable to .a very wide number ofspecific processes and gives a. large number of superior-new products. For example, a large number of different ladditivescan be employed. The followingi-llustratesthe range of materials which'havesuccessfully been added to synthetic organic polymenfil'anlents ac- Polymers which are incompatible with the polymer making. up the filament can be imbibed into the filamentary structure, with the result that these polymers "or UNIFORM I I l Chem 21, 2-ethoxy and ethyl .acrylate can be infused to give a permanent lowfriction surface. Flame-proof- .ing'agents, flame retardants, and the like such as his- (chloroethyl) vinyl phosphate and phylic acid can be infused. Cross-linking agents which cannot be added to the polymer before or during melt spinning (because they would cross-link during spinning) can, however, by the process of the present invention be added by this lowtempemature drawing technique, and then the cross-linking agents can be activated later. Inorganic salts, such as silver nitrate, potassium bichrornate, land the like can be employed. Wetting agents as well as hydrophobic agents can be imbibed. Anti-soilant additives are highly useful for some synthetic fibers. Adhesives and bonding agents can be infused to provide fibers and films with greater adhesion to rubber, to other polymers,= and to surfacemodifying chemicals. In addition, it is possible to'infuse into the filamentarystructure several substances at the same time, for example, mixtures of two totally. different types of dyes of like or different colors as well as three colors of the same type. Thus, one-can add a dyestuff, an anti-static agent, and a dye stabilize-r or ultra-violet absorber simultaneously and economically in asingle process step. In another modification, the imbibing process can be caused to occup step wise to imbibition of two, three or more different modifiers, one or more at each step, as already shown.

Most of the above-mentioned additives are in themselves non-reactive. However, a large number of reactive materials can be added to the polymer by the process of the present invention and subsequently or simultaneously reacted with another m aterial. examples above illustrate this principle, but further modifications arealso operative. For example, a dye mordant or dye assistant can be added during the crackdrawing process to facilitate later dyeing of the fiber.

Also, mixtures of polymers can be spun to form an undrawn filament, and then by the process of the present 40 invention one can imbibe a reactant which responds differentially to twoadiflerent types of polymer simultaneously during the process of the present invention. That 7 is, for example, an addition polymer and a compatible monomer or low molecular weight polymer can be combined in the spinning process, and during the drawing process of the present invention the low molecular weight material can be activated for further addition polymerization by imbibing .a'catalyst into the polymeric filament or film. i s V Furthermore, the present invention offers an improved method of obtaining grafted copolymer structures, for a graftable additive can be infused with a polymer structure during drawing, and then caused to graft onto the cific embodiment could prove extre-melyvaluable in laboratory techniques or chemical processing industries. Photographic chemicals, such as silver nitrate or potasslum dichromate, can be employed to give a filamentary material which is photographically active. Similarly, such invention can be highly valuable for chromatographic penetrate the filamentary structure and modify volume surface properties. Lubricants such as silicone oils, Syl

and gas-chromatographic techniques. Organic and inorganic additives can be employed which can be'caused v to change form following the infusion process. Metallic salts can be added and subsequently reduced as already shown to give a filament which is an unusually good conductor of heat or electricity.

Some of the All of the above additives can in general be applied according to the methods described to a number of synthetic organic polymers including polyethylene and polypropylene which nray be spun into fibers by any method, to polyesters, to acrylonitrile polymers and copolymers, and other orientable synthetic fibers. In addition to the chemical modifications already described, it has been found possible to perform the following chemical reactions within a fiber structure by imbibing one or more of the reactants simultaneously or successively: In polyanhydride reactions with formaldehyde, reaction of amide groups with monoisocyanates, chlorination employing SO CI with a catalyst, sulfonation, chlorosulfonation, oxidation, thio cyanation, and reactions of an imbibed additive with the basic polymer structure such as methoxym ethalation', reaction of a polyamide with methylol acrylamide and reduction of amide groups in the chain to secondary amine groups.

Chemical modification can also be employed following the irnbibition of a cross-linking agent as, for example, with diisocyanates, or phosgene, the introduction of methylborate followed by hydrolysis and heat linking, the introduction of pentaerythritol, glycerol and the like followed by ester interchange and similar cross linking cations.

Other non-reactive modifiers which can be employed include long rigid molecules such as quinquephenyl, and cheap organic or inorganic fillers.

Additional reactions which can be caused to take place within the fiber include the introduction of an organic salt such as hex-amethy-lene diarnmonium adipate followed by thermal polymerization within the fiber, deposition of low molecular weight, macrointermediates for long-chain polymers or monomers such as isobutylene butadiene, cross-linking polymers such as divinylbenzene, glycol dimethacrylate or other vinyl monomers. Furthermore, it is possible to introduce soluble organic or inorganic fillers which can subsequently be leached away to provide voids within the filamentary structure or to imbibe successively two coreactive chemicals which when in contact with each other will combine to form a gaseous product. Volatile liquids can also be imbibed and can be explosively expelled from the filamentary structure by passing the filament over a hot pin or other heated surface to produce :a filament with eroded or cratered surface. The treatments discussed above in connection with filaments are equally applicable to films with comparable results. In the claims the term modifying agent is intended to include one or more of the additives and modifying agents discussed above.

All of the above modifications of the present invention are applicable not only to films and fibers but to articles of larger dimensions whenever the flow involved during the molding or shaping process is sufficiently great to permit crack formation according to the principles already described. It is also possible to employ the principles of the present invention to obtain :gross products derived from filamentary structures, taking advantage of the modifying additives which can be added. For example, filaments of polyethylene terephthalate can be infused with a cross-linking agent such as divinyl benzene, ethylene diacylate, acylamide plus formaldehyde, boric acid, citric acid, glycerol and the like during the drawing process of the present invention. The fibers, without activation of the cross-linking material, can be cut into staple lengths and formed into non-woven batts or pellicles. After the pellicle has been formed, the cross-linking agent can be activated by known procedures to give a highly stable structure which is bonded in a much more intimate manner than is normally achievable.

The present invention can also be employed to give a filamentary threadline of varying appearance. For example, an undrawn filament containing a pigment or other agent introduced by either melt-dyeing or solutiondyeing can be drawn by the process of the present invention to introduce a second overdyeing material, coloring agent or other additive. This process can be applied by intermittently exposing the threadline to the cracking liquid. When the threadline is in the bath, it will draw according to the process of the present invention. When the threadline is not wet by the cracking agent, it will, of course, draw according to standard drawing processes known and described in the art. Equally well, the starting material can be an undrawn uncolored polymeric filament. This can be drawn and simultaneously infused with a dye, dye-site-former, wetting agent or the like according to the present invention in an intermittent fashion as described above. Then, subsequently, the drawn filament or film can be overdyed, or, if appropriate, a reactant can be applied to combine with the intermittently imbibed additive. Furthermore, two or more threadlines can be combined in parallel relationship, one having been treated according to the present invention, and another being of conventional nature. Another possible modification comprises two threadlines of similar or different basic polymeric structure, each having been infused with a different modifying additive according to the present invention. The modifications in physical properties of the combined threadline can thus be due to each of the two components separately, or as a synergistic and cumulative effect.

Furthermore, the present invention is not only applicable to those polymers already specifically indicated, but also to any polymer which, in filamentary or film form, can be caused to undergo a process of substantial irreversible elongation accompanied by molecular orientation, provided that the elongation-orientation step, generally referred to as drawing,v can be made to proceed by a sharp-neck step involving an abrupt change from the undrawn to the drawn condition.

Obviously, it is also necessary, in order to practice the present invention, that some method be available to cause surface cracks to occur and propagate across the threadline or film surface. Within this restriction, it has been found that the present invention can be practiced employing a wide range of polymers, including polyamides,'polyimides, polyesters, polyureas, polyurethanes, acetal resins, vinyl-type polymers, polyhydrocarbons, etc. Among the most preferred polymers, in addition to those shown in the examples, are poly(hexamethylene sebacamide), poly(e-caproarnide), poly(hexamethylene adipate), and poly(trans-p-hexahydroxylene terephthalate).

It will be apparent that many widely different embodiments of this invention may be made without departing from the spirit and scope thereof, and therefore it is not intended to be limited except as indicated in the appended claims.

I claim:

1. Drawn structures such as filaments, films, and the like consisting essentially of oriented synthetic organic linear fiber-forming polymeric material having a modifier other than a crack-inducing agent distributed within the said structure, the said modifier being present in short length variations of concentration along the length of the said structure.

2. A smooth drawn highly and continuously oriented structure such as filaments, films, and the like composed of synthetic organic linear fiber-forming polymeric material of essentially uniform density having a permanent modifier entrapped within the said structure, the said modifier being present in short length variations of at least 10 per inch along the length.

3. The structure of claim 2 in which theperiodicity of the variations is greater than 500 per inch.

4. The structure of claim 2 in which the periodicity of the variations is from 500 to 20,000 per inch.

5. The structure of claim 2 in which the modifier is a coloring agent.

6. The structure of claim 5 in which the coloring agent 17 is a dye which ideas not vdye the polymer appreciably by direct contact with the undrawn or completely, drawn polymer.

7. The structure of claim 2 in which the modifier is chemically reactive material.

8. The stnucture of claim 2 in the term of a film.

9. The structure of claim 2 in the [form of a filament.

10. The filament of claim 9 in which the polymer is polyethylene terephthalate.

11. The film of claim 8 in which the polymer is an aliphatic polyhydrocarbon.

12. The structure of claim 2 in which the polymer is a polyester; 1

13. The structure of claim 2 in which the polymer is a polyamide. i

14. The structure of claim 2.in which the polymer is a polyurethane.

15. The structure of claim 2 in which the polymer is 7 an aliphatic hydrocarbon.

Woods:

tions, vol. and T-631.

UNITED STATES PATENTS Carothers Feb. 16, 1937 Carothers Nov. 22, 1938 Lewis Apr. 7, 1942 Babcock July 7, 1942 Von Kohorn Nov. 17, 1942 Taylor June 15, 1943 Markwood July 4, 1944 'Freund July 4, 1944 Fields July 1, 1947 Pinsky July 4, 1950 Ladisch Oct. 7, 1952 Ladisch Apr. 6, 1954 Stanton et al. Mar. 6, 1956 Alles Oct. 23, 1956 OTHER REFERENCES Journal of the Textile Institute, Transac- 46 (September 1955), pages T-629, T-630, 

1. DRAWN STRUCTURES SUCH AS FILAMENTS, FILMS, AND THE LIKE CONSISTING ESSENTIALLY OF ORIENTED SYNTHETIC ORGANIC LINEAR FIBER-FORMING POLYMERIC MATERIAL HAVING A MODIFIER OTHER THAN A CRACK-INDUCING AGENT DISTRIBUTED WITHIN THE SAID STRUCTURE, THE SAID MODIFIER BEING PRESENT IN SHORT LENGTH VARIATIONS OF CONCENTRATION ALONG THE LENGTH OF THE SAID STRUCTURE. 